Positive expulsion fuel tank, and bladder dispenser therefor

ABSTRACT

A fuel tank including a metal shell defining a fuel compartment and having a discharge port at one end; a bladder module (housing) mounted on the shell at the end opposite the discharge port, and defining a bladder storage compartment; and a bladder unit including a flexible bladder, and a cage including a degree of flexibility; the bladder in relaxed condition is accordion folded, and thereby compacted, and is contained in the bladder module, and in such relaxed condition the accordion folds thereof, at least in great part, are contained in the flexible cage; pressurized gas is introduced into the bladder, and upon failure of the normal external pressure against the fuel, the gas pressure extends the bladder and forces the fuel out through the discharge port; as the bladder is so extended, the folds are released singly from the flexible cage, and each is fully expanded radially to engage the shell before the next one is released; there is a burst disc between the fuel compartment and the bladder compartment, segregating the fuel and bladder from mutual contact with the bladder is contracted.

11] 3,917,117 NOV. 4, 1975 1 POSITIVE EXPULSION FUEL TANK, AND BLADDER DISPENSER THEREFOR [75] Inventor: Norman Plotsky, Rockford, Ill.

[73] Assignee: Sundstrand Corporation, Rockford,

Ill.

22 Filed: May 21, 1973 21 Appl. No.2 361,956

[52] US. Cl 222/94; 222/386.5 [51] Int. Cl B65d 35/22 [58] Field of Search 222/3865, 389, 183, 94,

Primary Examiner-Even C. Blunk Assistant ExaminerJames M. Slattery Attorney, Agent, or Firm-Paul H. Gallagher [57] ABSTRACT A fuel tank including a metal shell defining a fuel compartment and having a discharge port at one end; a bladder module (housing) mounted on the shell at the end opposite the discharge port, and defining a bladder storage compartment; and a bladder unit including a flexible bladder, and a cage including a degree of flexibility; the bladder in relaxed condition is accordion folded, and thereby compacted, and is contained in the bladder module, and in such relaxed condition the accordion folds thereof, at least in great part, are contained in the flexible cage; pressurized gas is introduced into the bladder, and upon failure of the normal external pressure against the fuel, the gas pressure extends the bladder and forces the fuel out through the discharge port; as the bladder is so extended, the folds are released singly from the flexible cage, and each is'fully expanded radially to engage the shell before the next one is released; there is a burst disc between the fuel compartment and the bladder compartment, segregating the fuel and bladder from mutual contact with the bladder is contracted.

22 Claims, 13 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of6 3,917,117

US. Patent Nov. 4, 1975 Sheet 2 of 6 3,917,117

US. Patent Nov. 4, 1975 Sheet 3 of6 3,917,117

FIG: 4.

Sheet 4 0f 6 US. Patent Nov. 4, 1975 U.S. Patent Nov. 4, 1975 Sheet 5 of6 3,917,117

FIG 9.

U.S. Patent Nov. 4, 1975 She et 6 of 6 3,917,117

1/ I/I'I III/ I II III F l6 l2.

POSITIVE EXPULSION FUEL TANK, AND

' BLADDER DISPENSER THEREFOR FIELD OF THE INVENTION The invention resides in the field of fuel tanks used on a reserve or stand-by basis. Such tanks find most common use in airplanes or space vehicles, although they are not limited thereto. In the use of such tanks, the fuel is maintained in place by the pressure developed by the pump or other pressure means normally supplying fuel to the engine, but upon failure of that pressure means, the reserve fuelin the tank is expelled and it is conducted to the engine enabling continued operation until the emerg engy situation can be overcome.

OBJECTS OF THE INVENTION A broad object of the invention is to provide a reserve fuel tank of the foregoing general character, having a supply of fuel, and novel bladder means and means for extending it, for more effectively expelling the fuel from the tank.

Another broad object is to provide a reserve fuel tank of the foregoing character in which the bladder when inactive is compacted, and including novel means for controlling the extension of the bladder so that it is progressively extended, in a succession of increments, and each of such increments is fully extended or expanded before the next successive one is extended.

Another object is to provide a fuel tank of the kind referred to just immediately above, in which the bladder is included in a bladder unit, the bladder when relaxed and compacted, has a plurality of accordion folds, and the bladder unit includes means confining at least a great many of the folds, and the folds are released singly upon extension, each fold constituting an increment referred to.

Still another object is to provide a fuel tank of the kind referred to just immediately above, in which the bladder is tubular and elongated, the confining means is a cage including axially spaced rings engaging opposite sides of a plurality of accordion folds, and it possesses a degree of flexibility, successively releasing those folds upon application of pressure to the interior of the bladder.

A further object is to provide a fuel tank of the foregoing general character which includes a burst disc between the fuel compartment and bladder compartment, and wherein the cage has rigid elements, as of metal, and the bladder is flexible, and the cage is utilized in bursting the disc upon application of pressure to the bladder, one. of the rigid elements of the cage engages the disc and is utilized in bursting it, this step being more effective in so bursting the disc because of the rigidity of that cage element.

Still another object is to provide a fuel tank of the foregoing general type having novel construction and proportions for cooperatingwith various features of the tank, for example, the bladder has a main portion of relatively greater diameter for engaging the main portion of the tank shell, and a leading end portion of relatively lesser diameter, whereby to accommodate a smaller-dimensioned end of the tank shell, such as a hemispherical shape of the tank shell, or a certain form of bubble exclusion screen.

A further object is to provide a novel bubble exclusion screen.

Yet another object is to provide a bubble exclusion screen which includes a mesh enabling passage of liquid therethrough but not gas, and the mesh is corrugated, forming spaces between adjacent corrugations of capillary dimensions, thereby operative for holding liquid in those spaces by capillary action, and further increasing the prevention of the passage of bubbles therethrough.

A still further object is to provide a method of filling a fuel tank having burst discs therein.

DESCRIPTION OF A PREFERRED EMBODIMENT In thedr'awings,

FIG. 1 is an elevational view of the fuel tank made according to the present invention, with certain appurtenances operating therewith;

FIG. 2 is an axial sectional view of the fuel tank;

FIG. 3 is a view of the bladder unit utilized in the fuel tank, mostly in elevation, and generally in relaxed or compacted form;

FIG. 41s a perspective view of the bladder unit and the bladder module, separated from the tank, with the bladder partially extended;

FIG. 5 is aview similar to FIG. 4 but with the bladder fully extended;

FIG. 6 is a small scale axial sectional view of a portion of tank showing the bladder unit therein in partially extended condition;

FIG. 7 is a small scale axial sectional view of the end of the tank opposite that of FIG. 6 showing the bladder fully extended;

FIG. 8 is an axial sectional view of a portion of the fuel tank at the discharge end, showing the novel bubble exclusion screen of the invention;

FIG. 9 is a view mostly in section, of the bubble exclusion screen of FIG. 8;

FIG. 10 is a large scale view of the portion of FIG. 9 enclosed in dot-dash lines and indicated at 10;

FIG. 11 is a perspective view of the bubble exclusion screen shown in FIGS. 8-10; v

FIG. 12 is a sectional view taken at line 12, 12 of FIG. 11; and

FIG. 13 is a view similar to FIG. 7 but including a different form of bubble exclusion screen and the adaptability of the bladder thereto.

Referring in detail to the accompanying drawings, attention is directed first to FIG. 1 showing the overall fuel tank together with certain appurtenances cooperating therewith. The fuel tank is indicated generally at 20 and has a discharge end at 22 provided with a discharge port 24 (see FIG. 2).

A pump 26 normally pumps fuel from the main source of fuel, and constitutes the main means for providing fuel to the intended instrumentality, such as an airplane engine, having an outlet line 28 the latter communicating with a line 30 leading to the engine. The line 28 also communicates with a branch line 32 leading through the discharge port 24. In normal operation the pump 26, as indicated, provides the fuel to the engine, and in-that operation pressure is developed in the branch line 32 communicating with the tank and so long as pressure is maintained by the pump, the fuel is held in the tank, but in the event of failure of pump 26 and consequent loss of pressure therefrom, the tank 20 provides the stand-by fuel which is forced out through the discharge port 24, the branch line 32 and the line 30 to the engine. This general arrangement just described is of course known.

Also associated with the fuel tank is another tank 34 containing a supply of gas (nitrogen) and leading from this tank is a line 36 leading to a gas inlet port 38 at a gas inlet end opposite the discharge end and into the bladder compartment, as described hereinbelow, for

extending the bladder upon a predetermined differential of that gas pressure over the pressure exerted by the pump 26 against the fuel in the fuel compartment.

Attention is next directed to FIG. 2 showing the tank in axial sectional view. The tank 20 includes a container 40 made up of two main parts, namely a shell 42 and a bladder module or housing 44. The shell has a main central portion 46 cylindrical in shape which merges into the discharge end 22 identified above which is hemispherical in shape.

For convenience in the description herein, the discharge end 22 may also be referred to as the lower end, and the opposite end as the upper end. While it may be desired that the fuel tank assume such position, it may also assume other positions and the designations just referred to are to be interpreted with that understandmg.

A relief tube 48 is provided on the inner surface of the shell and extends'longitudinally of the shell substantially or nearly throughout the length thereof. This tube is open at both ends and cooperates in the forcing the fuel out by the bladder, as described hereinbelow.

The shell 42 provides a fuel compartment 50. The shell 42 is preferably of aluminum alloy but it may be made of other materials instead, consideration being given to the compatibility of the metal used with the fuel'to be contained therein.

The bladder module or housing 44 is also shown in FIGS. 3, 4 and and its shape can readily be observed from those figures. The housing includes a dome shaped body portion 52 having an open end'54, and forming a bladder compartment 56. The housing has a flange 58 surrounding its open end and provided with apertures 60 for receiving cap screws 61 for securing it to the upper end of the shell, the latter having suitable conformations with tapped holes for that purpose. The housing 44 includes the gas entry port 38 identified above through which the gas (nitrogen) enters the bladder compartment and flows into the bladder for extending the latter when it is to be extended.

Attention is next directed to FIGS. 2 and3 showing the bladder in folded retracted condition. The bladder is identified at 62 and is associated with a cage 64, together forming a'bladder unit identified generically at 66. In the following description of the bladder unit attention may be given also to FIGS. 4 and 5 as well as FIGS. 2 and 3. The bladder 62 is of elastomeric material, stretchable in both directions. It is tubular in shape and elongated when extended (FIGS. 2, 6and 7). It includes a main portion 68 of relatively great diameter and a leading end portion 70 of relatively lesser diameter. The bladder has a closed leading end 72 but is open at the'other end 74 (FIGS. 2 and 3).

The bladder is provided with folds 76 in the large portion 68 and similar folds 78 in the leading end portion 70. These folds fit close together,-and may even interengage when the bladder is relaxed or contracted, but when sufficient pressure is applied to the interior of the bladder, it extends axially and expands radially, the folds straighten out and the bladder engages the inner surface of the tank shell throughout its length.

The cage 64 possesses a degree of flexibility as indicated and includes two metal rings 80 (rigid) surround- 4. ing the bladder. The rings are interconnected with a single length of wire, or filament 82 laced through apertures in the rings in back-and-forth arrangement and the ends of the wire are interconnected by suitable connecting means 84 crimped thereon.

The length of the wire 82 is pre-selected to space the plates 80 apart in axial direction a distance designed to confine a plurality of the folds 76, these rings extending between the folds and engaging opposite sides of the end ones of those folds individually identified 76a, 76b.

In the preferred form this cage confines less'than all of 1 the folds 76 but the particular number is not of the essence, and it may be more or less than the actual number represented in FIG. 3. The leading end portion of the bladder is not confined by the cage but is enabled to pass through the central aperture of the lower ring when otherwise free to do so. i I The bladder unit is incorporated in the tank con tainer as best represented in FIG. 2. The bladder unit in folded and retracted form is placed in the bladder compartment 56 with the open upper end 74 of the bladder engaging the end surface of that bladder compartment.

The bladder unit is mechanically secured in the bladder compartment by suitable means such as a ring 86 (see also FIG. 7)--engaging the inner edge-portion 88 of the. top fold of the bladder. The ring 86 is in turn secured in place by suitable means such as cap screw 90 passing through theupper wall of the bladder module.

The fuel compartment 50 and the bladder compartment 56 are separated by a burst disc 92 (FIG. 2)

gripped between the shell 42 and thebladder module at 94, and hermetically sealed as by suitable sealing means 96. The reduced diameter leading end portion 70 of the bladder is confined by this burst disc within the bladder chamber. The lower ring of the cage also engages the burst disc and of course this ring is within the internal diameter of the open end of the tank shell.

I A discharge burst disc 98 (FIG. 2) is provided in the discharge line 28, or at any convenient place within the outlet port 24 and the fuel line 30 leading to the engine.

In the normal operation of the pump 26 according to. the operation of the engine, the pressure in the lines 32 developed by the pump 26 maintains the fuel in the tank in stable condition. The nitrogen in the tank 34 is under a certain pressure, and the pressure from the line.

32 reacts also against the pressure of the nitrogen, the nitrogen as indicated above, passing through the inlet port into the interior of the bladder (FIG. 2). If the pump should fail, the normal pressure developed thereby fails and when it reaches a predetermined point below the standing pressure of the nitrogen, the nitrogen working through the bladder breaks the burst disc 92 and the bladder extends into the tank shell, and it.

breaks the discharge burst disc 98 as. well. On this feature it is to be noted that since the lowerring 80 of the cage directly engages the burst disc, and because of its rigidity, it aids in breaking the disc in contrast to the Upon continued extension, the second fold from the top is released or pulled out of the cage, as represented in FIG. 6, and the second fold is expanded radially into engagement with the inner surface of the shell. The bladder wall is extended also between adjacent folds so that the bladder engages the tank shell uniformly throughout its length. In FIG. 6 the line 100 represents the division between adjacent folds. The bottom fold 76 remains secured to the lower ring 80 throughout the full extension, as shown in FIG. 7.

The extension of the bladder continues until it reaches the discharge end or bottom of the tank as represented in FIG. 7 where the closed end 72 of the bladder engages the lowermost portion of the tank shell. In this connection it is pointed out that the leading end portion 70 of the bladder accomodates the hemispherical shape of the lower end of the tank shell, in that the rings 80 of the cage engage the surface of the shell at a point above the ultimate bottom, but the reduced leading end portion of the bladder reaches that surface. By virtue of the flexible connection between the rings 80, the upper ring ultimately engages the fold 76 on the lower ring, as shown in FIG. 7, to permit the bladder to exhaust substantially all the fuel.

The by-pass tube 48 (FIG. 2) provides for the passage of any fuel that may have been trapped at the top of the tank shell so that it can flow through that tube and discharge at the extreme bottom beyond the lower end of the bladder.

The tank is provided with suitable means used in filling it, such as a fill tube 102 (FIG. 1), as well as other appurtenances, such as leakage detector, over pressure burst disc, temperature burst disc, etc.

The invention also includes a novel bubble exclusion means. It is of course desirable in the use of liquid fuel that gas bubbles do not reach the engine, and various devices have been constructed for that purpose. The use of a fine mesh screen for that purpose is known, such being effective for permitting the passage of liquid therethrough but preventing the passage of the gas bubbles therethrough. The bubble exclusion screen of the present invention incorporates that general principle, and also incorporates a novel construction which is more effective than those heretofore known. Attention is directed to FIGS. 8 to 12 inclusive. FIG. 8 shows the lower portion of the tank shell 42. This figure is semidiagrammatic and devoid of details, but shows the novel bubble exclusion screen 104 (also referred to merely as a bubble screen) having a main upright portion 106 and a lower outlet fitting 108 applied to the discharge port 24, the fuel compartment communicating with the discharge port only through the bubble screen. FIG. 11 shows the bubble screen in perspective while FIG. 12 shows the construction in section. The bubble screen construction includes a back plate 110 preferably curved transversely and secured on the front thereof is the fine mesh wire screen 112. The screen is secured to the edges of the plate 110 as shown at 114, against passage of fluid therethrough, the screen-and back plate defining a chamber 116 therebetween. The upper end of the chamber is closed by an imperforate element 115 while the fitting 108 closes the chamber at the lower end, the fitting having also a flange or edge 120 crimped on the lower end of the screen and closing the chamber 116 at that point. A tube or pipe 122 is disposed in the chamber 1 l6 and it extends longitudinally therein. The tube 122 is secured in the chamber in a suitable manner such as by welding as indicated at 124 and reinforces the bubble screen. The tube 122 is provided with a series of apertures 126 (FIGS. 9 and 10) for free flow of liquid fluid in the chamber relative to the tube, and the tube communicates with the chamber 116. A perforate front plate 127 covers the bubble screen and is secured to the back plate and screen 112 and has apertures 129 to admit fluid to the screen 112.

The screen 112 is corrugated transversely, forming a plurality of closely spaced corrugations 128, with spaces therebetween. These corrugations are dimensioned approximately 1 /s8 inch center to center and the spaces 130 therebetween are of capillary nature, holding quantities of liquid fuel in those spaces.

The bladder upon extension thereof, forces the liquid fuel through the screen and it passes into the chamber 116 and then to the fitting 108 and the discharge port. The holding of the liquid fuel in the capillary spaces has been found to provide a great advantage in the intended purpose, i.e., passage of liquid and exclusion of gas bubbles.

The reduced. leading end 70 also is effective for accommodating bubble screens of other known types. FIG. 13 shows a bubble screen 132, of a kind heretofore known, disposed at the center of the discharge end of the tank. This screen extends upwardly quite a distance, and the cage 64 of the bladder unit engages the hemispherical surface of the discharge end of the tank,

but the reduced end portion 70 of the bladder folds over the bubble screen and in doing so still reaches the extreme bottom end of the tank.

The invention encompasses a novel method of filling the tank with fuel, considering the use of burst discs therein. FIG. 1 represents such a step in filling. The tank 40 shows the fill tube 102 through which the fuel passes into the fuel compartment. The burst disc 92 between the fuel compartment and the bladder compartment is shown as well as the burst disc 98 at the discharge end. To fill the tank a vacuum is formed therein as through pipe 102 and thereby draws in the fuel. To relieve the effect of such vacuum from the burst discs 92 and 98, vacuum is also formed on the opposite sides of both of those discs, the line 36 producing a vacuum in the bladder chamber and the line 32 producing a vacuum on the opposite side of the discharge burst disc 98.

I claim:

1. A fuel tank comprising,

a container including a shell defining a main fuel compartment and having a discharge port at one end,

means on the shell at the end thereof opposite the discharge port defining a bladder compartment communicable with the main fuel compartment,

a bladder unit including a bladder and bladder confining means,

the bladder being tubular and generally elongated when extended, and being contractible axially to a length greatly less than its extended length, and having folds in its contracted condition,

the bladder confining means engaging opposite ends of the bladder when the bladder is contracted, the bladder when contracted being disposed in the bladder compartment and the container having an inlet port adapted for introduction of fluid pressure therethrough into the bladder,

the bladder being responsive to fluid pressure therein of predetermined value greater than that in the fuel compartment and extendable by that greater pressure into the fuel compartment and being thereby 7 operative for expelling the fuel from the fuel compartment, and the confining means being movable during such extension for releasing the folds singly from the end adjacent the bladder compartment.

2. A fuel tank according to claim 1 wherein the shell includes a main portion of cylindrical shape, and the bladder when extended axially and expanded radially forms a substantially cylindrical shape, and the shell and the bladder are relatively dimensioned so that the bladder substantially engages the inner surface of the shell throughout its cylindrical extent.

3. A fuel tank according to claim 1 wherein the shell of the tank is of reduced dimensions at the end opposite the bladder compartment, and the bladder has a leading end of reduced diameter operative for engaging that reduced dimension end of the shell, andsubstantially completely filling it.

4. A fuel tank according to claim 3 wherein the bladder in contracted condition is of greatly less axial dimension than when extended, and is compacted in the bladder compartment in a corresondingly small dimension, and

when the bladder is extended, the bladder confining means is carried by the extended end of the bladder toward the reduced dimension end of the shell, the bladder confining means is of a radial dimension close to the radial dimension of the shell, and when the bladder approaches the reduced end of the shell opposite the bladder compartment, the confining means engages the portions of the shell just before the reduction from cylindrical shape, and is restricted thereby from further movement, and the reduced dimension of the leading end of the bladder extends into the lowermost end of the shell, beyond the postion of stoppage of the bladder confining means, whereby to substantially fill,

that portion of the shell and expel fuel therefrom.

5. A fuel tank according to claim 3 wherein the bladder in contracted condition is of greatly less axialdimension than when extended, and is compacted in the bladder compartment in a correspondingly small dimension, and

when the bladder is extended, the confining means is carried by the extended end of the bladder toward the reduced dimension end of the shell,

the confining means is of a radial dimension close to the radial dimension of the shell, and when the bladder approaches the reduced end of the shell opposite the bladder compartment, the confining means engages the portions of the shell just before the reduction from cylindrical shape, and is restricted thereby from further movement,

and the reduced dimension of the leading end of the bladder extends into the lowermost end of the shell, beyond the position of stoppage of the confining means, whereby to substantially fill that portion of the shell and expel fuel therefrom.

6. A fuel tank according to claim 1 wherein the confining means includes a flexible cage, the flexible cage including a pair of axially spaced rings engaging opposite ends of the folds of the bladder and as the folds are released from the flexible cage, the gas pressure in the interior of the bladder retains those yet remaining ones against those rings to maintain a holding condition of the folds remaining.

7. A fuel tank as defined in claim 6 wherein the bladder fold adjacent the discharge port is secured to the ring adjacent the discharge port, so that the pressure of gas in the bladder holds the confining means centrally in the shell.

8. A fuel tank according to claim 7 wherein the means interconnecting the rings includes a single strand or filament laced through and between the rings enabling the relative angular movement between the rm s.

9 A fuel tank according to claim 6 wherein the flexible cage on the bladder includes, in addition to the rings mentioned, flexible strand means connected between the rings, whereby to enable flexing in a wobbling nature of the two rings relative to each other as the folds are released from between the rings.

10. A fuel tank as defined in claim 9 wherein the ring adjacent the discharge port is engageable with the shell adjacent the discharge port and the ring adjacent the bladder compartment is thereupon movable toward the first mentioned ring to minimize the area of the bladder held away from the shell by the confining means.

11. A fuel tank comprising,

a container including a shell defining a main fuel compartment and having a discharge end and a gas inlet end opposite the discharge end and having a discharge port atthe discharge end,

a bladder module on the shell at the gas inlet end of the latter defining a bladder compartment communicable with the fuel compartment,

a bladder unit including a bladder and confining means,

the bladder being tubular and generally elongated, and being contractable axially to a length greatly less than its extended length, and having folds in its contracted condition,

the bladder having an open end secured to the blad der module and the tank having a gas inlet port in the bladder module communicating with the interior of the bladder, the bladder being responsive to gas pressure therein of predetermined value greater than that in the main fuel compartment and bladder when the latter is contracted and also including means interconnecting the plates enabling relative movement therebetween the bladder unit, when the bladder is contracted, being disposed in the bladder compartment,

the confining means being a self-contained assemblage and movable substantially as a unit with the associated portion of the bladder from the bladder compartment to the main fuel compartment, as the bladder is extended,

the confining means being operative in response to introduction of gas under pressure into the bladder for so releasing the folds of the bladder singly first from the gas inlet end thereof and progressively along the bladder toward the opposite end of the latter, whereby to enable the increments of the bladder, as determined by the folds to fill the main fuel compartment progressively from the gas inlet end to the discharge end.

12. A fuel tank according to claim 4 wherein a burst disc is interposed between the fuel compartment and the bladder compartment, and it normally maintains the bladder in compacted condition in the bladder compartment, and wherein extendable by that greater pressure into the main 9 upon release of normal pressure from the fuel compartment the pressure of the gas in the bladder expands the bladder and burst the burst disc and expands and drives the fuel from the fuel compartment.

13. A fuel tank according to claim 12 wherein the bladder confining means includes rigid elements, and at least one of them bears against the burst disc between the bladder compartment and the fuel compartment and assists in breaking the burst disc in addition to the pressure in the bladder working on the flexible material of the bladder which without rigid discs would exert the total force against the burst disc for bursting it.

14. A fuel tank according to claim 11 and including a bubble screen of generally flat form at one side of the tank and leading to the discharge end and communicating with the discharge port,

the confining means is of such dimensions as to substantially pass by the bubble screen without interference therewith, and the fuel as it is expelled from the fuel tank by the bladder progressively flows through the bubble screen.

15. A fuel tank according to claim 11 whereinthe bladder when extended extends substantially the full length of the shell, and the construction includes a tube secured to the surface of the shell independently of the bladder, so that when the bladder is extended it engages the surface of the shell and the tube, but the tube remains open at the top and bottom whereby to provide passage of fuel from the top to the bottom that may otherwise tend to be trapped by the bladder.

16. A fuel tank according to claim 11 wherein the shell of the tank has a main portion of uniform diameter and a portion at its discharge end of reduced dimenson,

the bladder includes a main portion of relatively large diameter and a leading end portion of reduced diameter,

at least one of the plates of the confining means is in the form of a ring having a central opening and the reduced end portion of the bladder extends through that opening,

the plates, including said ring are rigid and the ring is engageable with the inner surface of the shell at a 4 portion adjacent to but spaced from the discharge end of the fuel compartment, and the reduced end portion of the bladder is extendable through the central opening of said ring and engageable with the farmost and reduced dimension end of the wall of the tank. 17. A fuel tank according to claim 16 wherein the bladder fold engaging the ring adjacent the discharge 10 port is secured to such ring, and the presssure of gas in the bladder holds the confining means centrally in the shell.

18. A fuel tank according to claim 17 wherein the second ring adjacent the bladder compartment is movable toward the other ring when the latter ring contacts the shell adjacent the discharge end to minimize the area of the bladder held away from the shell by the confining means.

19. A fuel tank according to claim 16 wherein the plates of the confining means are in the form of rings and the folds which are engaged by the rings are formed in the large diameter portion of the bladder, and the gas pressure within the bladder expands those folds between the rings whereby to maintain the end folds in firm engagement with the rings to prevent release of the folds from the rings except when the bladder is extended by gas pressure to such an extent that the folds are forcibly released from between the rings.

20. A fuel tank according to claim 19 wherein the plates of the confining means are stopped in their movement toward the discharge end of the fuel tank, and the central reduced diameter portion of the bladder extends beyond the plates,

the fuel tank has a bubble screen centrally at the discharge end thereof communicating with the discharge port, and extending axially toward the bladder compartment, and the reduced diameter extended end of the bladder encompasses the bubble screen and substantially fills the space in the tank around the bubble screen to the extended end thereof.

21. A fuel tank according to claim 19 wherein the confining means includes, in addition to the rings mentioned, a continuous and single strand wire laced between the rings and having its ends secured together, whereby to enable flexing in a wobbling nature of the two rings relative to each other as the folds are released from between the rings.

22. A fuel tank according to claim 21 wherein the ring adjacent the discharge port is engageable with the shell at a position close to the discharge port, and the other ring is movable toward the first mentioned ring, whereby to minimize the axial dimension of the confining means as defined by the rings so that as the ring adjacent the discharge port engages the shell, the proximity of the two rings reduces any portion of the shell not engageable by the bladder, and correspondingly increases that portion of the shell substantially and effectively engaged by the bladder for maximum expulsion of fuel from the tank.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,917,117 Dated November i, 1975 Inventor (5) Norman P1013 sky It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 10, "1 1/8 8" should be --l/8--;

Column 8, line 6n, Claim 12, line 1, "Claim i" should be Claim 11.

Signed and Scaled this tenth Day Of February 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner aj'Parems and Trademarks 

1. A fuel tank comprising, a container including a shell defining a main fuel compartment and having a discharge port at one end, means on the shell at the end thereof opposite the discharge port defining a bladder compartment communicable with the main fuel compartment, a bladder unit including a bladder and bladder confining means, the bladder being tubular and generally elongated when extended, and being contractible axially to a length greatly less than its extended length, and having folds in its contracted condition, the bladder confining means engaging opposite ends of the bladder when the bladder is contracted, the bladder when contracted being disposed in the bladder compartment and the container having an inlet port adapted for introduction of fluid pressure therethrough into the bladder, the bladder being responsive to fluid pressure therein of predetermined value greater than that in the fuel compartment and extendable by that greater pressure into the fuel compartment and being thereby operative for expelling the fuel from the fuel compartment, and the confining means being movable during such extension for releasing the folds singly from the end adjacent the bladder compartment.
 2. A fuel tank according to claim 1 wherein the shell includes a main portion of cylindrical shape, and the bladder when extended axially and expanded radially forms a substantially cylindrical shape, and the shell and the bladder are relatively dimensioned so that the bladder substantially engages the inner surface of the shell throughout its cylindrical extent.
 3. A fuel tank according to claim 1 wherein the shell of the tank is of reduced dimensions at the end opposite the bladder compartment, and the bladder has a leading end of reduced diameter operative for engaging that reduced dimension end of the shell, and substantially completely filling it.
 4. A fuel tank according to claim 3 wherein the bladder in contracted condition is of greatly less axial dimension than when extended, and is compacted in the bladder compartment in a corresondingly small dimension, and when the bladder is extended, the bladder confining means is carried by the extended end of the bladder toward the reduced dimension end of the shell, the bladder confining means is of a radial dimension close to the radial dimension of the shell, and when the bladder approaches the reduced end of the shell opposite the bladder compartment, the confining means engages the portions of the shell just before the reduction from cylindrical shape, and is restricted thereby from further movement, and the reduced dimension of the leading end of the bladder extends into the lowermost end of the shell, beyond the postion of stoppAge of the bladder confining means, whereby to substantially fill that portion of the shell and expel fuel therefrom.
 5. A fuel tank according to claim 3 wherein the bladder in contracted condition is of greatly less axial dimension than when extended, and is compacted in the bladder compartment in a correspondingly small dimension, and when the bladder is extended, the confining means is carried by the extended end of the bladder toward the reduced dimension end of the shell, the confining means is of a radial dimension close to the radial dimension of the shell, and when the bladder approaches the reduced end of the shell opposite the bladder compartment, the confining means engages the portions of the shell just before the reduction from cylindrical shape, and is restricted thereby from further movement, and the reduced dimension of the leading end of the bladder extends into the lowermost end of the shell, beyond the position of stoppage of the confining means, whereby to substantially fill that portion of the shell and expel fuel therefrom.
 6. A fuel tank according to claim 1 wherein the confining means includes a flexible cage, the flexible cage including a pair of axially spaced rings engaging opposite ends of the folds of the bladder and as the folds are released from the flexible cage, the gas pressure in the interior of the bladder retains those yet remaining ones against those rings to maintain a holding condition of the folds remaining.
 7. A fuel tank as defined in claim 6 wherein the bladder fold adjacent the discharge port is secured to the ring adjacent the discharge port, so that the pressure of gas in the bladder holds the confining means centrally in the shell.
 8. A fuel tank according to claim 7 wherein the means interconnecting the rings includes a single strand or filament laced through and between the rings enabling the relative angular movement between the rings.
 9. A fuel tank according to claim 6 wherein the flexible cage on the bladder includes, in addition to the rings mentioned, flexible strand means connected between the rings, whereby to enable flexing in a wobbling nature of the two rings relative to each other as the folds are released from between the rings.
 10. A fuel tank as defined in claim 9 wherein the ring adjacent the discharge port is engageable with the shell adjacent the discharge port and the ring adjacent the bladder compartment is thereupon movable toward the first mentioned ring to minimize the area of the bladder held away from the shell by the confining means.
 11. A fuel tank comprising, a container including a shell defining a main fuel compartment and having a discharge end and a gas inlet end opposite the discharge end and having a discharge port at the discharge end, a bladder module on the shell at the gas inlet end of the latter defining a bladder compartment communicable with the fuel compartment, a bladder unit including a bladder and confining means, the bladder being tubular and generally elongated, and being contractable axially to a length greatly less than its extended length, and having folds in its contracted condition, the bladder having an open end secured to the bladder module and the tank having a gas inlet port in the bladder module communicating with the interior of the bladder, the bladder being responsive to gas pressure therein of predetermined value greater than that in the main fuel compartment and extendable by that greater pressure into the main fuel compartment and being thereby operative for expelling the fuel from the fuel tank, the confining means including axially spaced plates engaging end ones of a plurality of folds of the bladder when the latter is contracted and also including means interconnecting the plates enabling relative movement therebetween the bladder unit, when the bladder is contracted, being disposed in the bladder compartment, the confining means being a self-contained assemblage and movable sUbstantially as a unit with the associated portion of the bladder from the bladder compartment to the main fuel compartment, as the bladder is extended, the confining means being operative in response to introduction of gas under pressure into the bladder for so releasing the folds of the bladder singly first from the gas inlet end thereof and progressively along the bladder toward the opposite end of the latter, whereby to enable the increments of the bladder, as determined by the folds to fill the main fuel compartment progressively from the gas inlet end to the discharge end.
 12. A fuel tank according to claim 4 wherein a burst disc is interposed between the fuel compartment and the bladder compartment, and it normally maintains the bladder in compacted condition in the bladder compartment, and wherein upon release of normal pressure from the fuel compartment the pressure of the gas in the bladder expands the bladder and burst the burst disc and expands and drives the fuel from the fuel compartment.
 13. A fuel tank according to claim 12 wherein the bladder confining means includes rigid elements, and at least one of them bears against the burst disc between the bladder compartment and the fuel compartment and assists in breaking the burst disc in addition to the pressure in the bladder working on the flexible material of the bladder which without rigid discs would exert the total force against the burst disc for bursting it.
 14. A fuel tank according to claim 11 and including a bubble screen of generally flat form at one side of the tank and leading to the discharge end and communicating with the discharge port, the confining means is of such dimensions as to substantially pass by the bubble screen without interference therewith, and the fuel as it is expelled from the fuel tank by the bladder progressively flows through the bubble screen.
 15. A fuel tank according to claim 11 wherein the bladder when extended extends substantially the full length of the shell, and the construction includes a tube secured to the surface of the shell independently of the bladder, so that when the bladder is extended it engages the surface of the shell and the tube, but the tube remains open at the top and bottom whereby to provide passage of fuel from the top to the bottom that may otherwise tend to be trapped by the bladder.
 16. A fuel tank according to claim 11 wherein the shell of the tank has a main portion of uniform diameter and a portion at its discharge end of reduced dimension, the bladder includes a main portion of relatively large diameter and a leading end portion of reduced diameter, at least one of the plates of the confining means is in the form of a ring having a central opening and the reduced end portion of the bladder extends through that opening, the plates, including said ring are rigid and the ring is engageable with the inner surface of the shell at a portion adjacent to but spaced from the discharge end of the fuel compartment, and the reduced end portion of the bladder is extendable through the central opening of said ring and engageable with the farmost and reduced dimension end of the wall of the tank.
 17. A fuel tank according to claim 16 wherein the bladder fold engaging the ring adjacent the discharge port is secured to such ring, and the presssure of gas in the bladder holds the confining means centrally in the shell.
 18. A fuel tank according to claim 17 wherein the second ring adjacent the bladder compartment is movable toward the other ring when the latter ring contacts the shell adjacent the discharge end to minimize the area of the bladder held away from the shell by the confining means.
 19. A fuel tank according to claim 16 wherein the plates of the confining means are in the form of rings and the folds which are engaged by the rings are formed in the large diameter portion of the bladder, and the gas pressure within the bladder expands those folds between the rings whereby to maintain the end folds in firm engagement with the rings to prevent release of the folds from the rings except when the bladder is extended by gas pressure to such an extent that the folds are forcibly released from between the rings.
 20. A fuel tank according to claim 19 wherein the plates of the confining means are stopped in their movement toward the discharge end of the fuel tank, and the central reduced diameter portion of the bladder extends beyond the plates, the fuel tank has a bubble screen centrally at the discharge end thereof communicating with the discharge port, and extending axially toward the bladder compartment, and the reduced diameter extended end of the bladder encompasses the bubble screen and substantially fills the space in the tank around the bubble screen to the extended end thereof.
 21. A fuel tank according to claim 19 wherein the confining means includes, in addition to the rings mentioned, a continuous and single strand wire laced between the rings and having its ends secured together, whereby to enable flexing in a wobbling nature of the two rings relative to each other as the folds are released from between the rings.
 22. A fuel tank according to claim 21 wherein the ring adjacent the discharge port is engageable with the shell at a position close to the discharge port, and the other ring is movable toward the first mentioned ring, whereby to minimize the axial dimension of the confining means as defined by the rings so that as the ring adjacent the discharge port engages the shell, the proximity of the two rings reduces any portion of the shell not engageable by the bladder, and correspondingly increases that portion of the shell substantially and effectively engaged by the bladder for maximum expulsion of fuel from the tank. 